Superficial Musculo Aponeurotic System(SMAS)

1. PRESENTED BY :AKSHAY SHAH (OSPG 3)
GUIDED BY :Dr. NEHA VYAS
Dr. NITU SHAH
ANATOMY OF PREAURICULAR REGION

2. INTRODUCTION
The human face comprises many anatomical components that contribute to appearance and
function.

3. SKIN
Skin forms the outer face layer and contains the outer epidermis and the underlying dermis.
The epidermis contains several cell layers.
The dermis is composed of collagen and elastin fibers embedded in a ground matrix.
Facial skin thickness and composition varies according to position and person.
Its thickness ranges from 0.5 mm on eyelids to 1.5 mm on cheeks.
The skin over the cheek and submental area contains more subcutaneous tissue and is more
mobile and easily elevated.

4. SUBCUTANEOUS FAT
Under the skin, the face contains several superficial fat compartments.
The subcutaneous layer has 2 components,
1.subcutaneous fat
2.the fibrous retinacular cutis that connects the dermis with the underlying SMAS

5. They are the nasolabial fat compartment; temporal-cheek fat pads, which cover the cervical,
cheek, and forehead regions; orbital fat pads; and the jowl fat compartment in the lower
third of the face.
Each compartment is separated by fascial tissue and septae (Prendergast, 2013). With
aging, volume loss occurs at different rates in the fat compartments, which leads to less
smooth contours on facial surfaces

6. SUPERFICIAL MUSCULOAPONEUROTIC SYSTEM
Deep to the subcutaneous layer is the SMAS
Concept given by Teisser & defined by Mitz and Peyronie in 1976.
Synonyms:
In scalp – galea aponeurotica
In temporal region – temporoparietal fascia, superficial temporal fascia or suprazygomatic
SMAS
Below zygomatic arch – parotideomasseteric fascia
SMAS is a tissue sheet of collagen and elastin fibers, and fat cells extending from the neck up to
the forehead .
It plays a key role in facial expression by connecting mimetic muscles to the dermis.

7. Types:
Type I SMAS occurs in the forehead, parotid, zygomatic, and infraorbital areas and
comprises fibrous septae.
Type II SMAS is a dense mesh of collagen, elastin, and muscle fibers and is found in the
lip area .

8. SMAS thicknesses vary throughout the face from 2 to 3 mm.
The SMAS is a continuous fibromuscular layer that envelopes the face and neck; it is
considered to be a well defined portion of the superficial facial fascia that forms a continuous
sheath through the face and neck extending into the malar region of the lips and nose.
The SMAS extends downward at the superficial cervical fascia and upward at the
temporoparietal fascia
Anatomically, the SMAS lies inferior to the zygomatic arch and superior to the muscular belly
of the platysma
The SMAS that lies over the parotid gland is fixed and immobile.

9. Structure and Function
The SMAS connects the facial muscles to the dermis, and its purpose
is to transmit, distribute, and amplify the activity of all facial
muscles .
It has a close relationship with the most superficial fascial planes of
the face and neck area.
SMAS act as a central tendon for a coordinated muscular contraction
of the face and providing a functional role of movement for
expression

11. The SMAS can also vary in thickness from patient to patient and in different regions
of the face.
It is thickest over the parotid gland and the temporal region (temporoparirital
fascia) and within the scalp (galea).
It is much thinner over the masseter muscles and is thinnest in the malar region.
SMAS thicknesses vary throughout the face from 2 to 3 mm

12. The superficial surfaces of the muscles of facial
expression are surrounded by superficial fascia.
Deep to this layer is the deep facial fascia, which is
continuous layer of the deep cervical fascia and parotid
fascia.
In the cheek, the branches of the facial nerve lie deep to
the deep facial fascia. These facial nerve branches run
deep to the fascia once they reach their specific muscle;
they penetrate the deep facial fascia

13. RETAINING LIGAMENTS
Retaining ligaments are fibrous connective tissue condensations that either anchor skin to
bone (also known as true retaining ligaments) or soft tissue layers to each other (also known
as false retaining ligaments).
True ligaments include zygomatic ligament anchors the dermis near the inferior border of the
zygomatic arch. The mandibular retaining ligament connects mandibular bone to the dermis.
The orbicularis retaining ligament anchors the dermis in the anterior orbital rim region .
False retaining ligaments include the masseteric and platysma-auricular ligaments.
The masseteric ligament is positioned along the anterior masseter muscle border and connects
the SMAS and dermis. With aging, the retaining ligaments become weaker, which results in
tissue sagging.

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7-Mar-17

15. Blood Supply and Lymphatics
The Superficial musculoaponeurotic system receives its blood supply from the
Transverse facial artery, which also supplies blood to a broad region of the
lateral malar area of the face.
The SMAS also partially receives arterial supply from the musculocutaneous
perforators of the facial artery.
The small lymphatic vessels lying deep to the SMAS mainly flow into the
preauricular or submandibular lymph nodes, which then drain into the anterior
cervical chain.

16. Nerves
The branches of the Facial nerve are the most anatomically relevant nerves that lie in the vicinity
to the SMAS and the facial muscles & associated fascial layers.
The facial nerve exits the skull inferior to the tragus of the ear. The proximal branches of the
facial nerve primarily the temporal, zygomatic, and marginal mandibular nerves course deep to
the SMAS after exiting the parotid gland.
.

17. Atlas of temporomandibular joint surgery – Peter D Quinn 2nd ed

18. Atlas of temporomandibular joint surgery – Peter D Quinn 2nd ed

19. Atlas of temporomandibular joint surgery – Peter D Quinn 2nd ed

20. Great auricular nerve is originates from the cervical plexus, passes
inferiorly to traverse the sternocleidomastoid muscle about 6-cm
inferior to the auditory canal, and runs just deep to the SMAS along
the course of the external jugular vein.
The only nerves which traverse superficial to the SMAS are the
sensory branches from the trigeminal nerve.
Arises from posterior part of mandibular division of CN V
Atlas of human anatomy – Frank H Netter 6th ed
Runs beneath lateral pterygoid muscle.
Passes from medial surface of condyle & emerges on to the
face behind the TMJ within the superior surface of the
parotid gland.
Ascends posterior to the superficial temporal vessels, passes
over the posterior root of the zygoma, and divides into
superficial temporal branches

21. APPLIED ANATOMY
The subcutaneous fatty layer is of variable thickness and envelops the mimetic
muscles. Anatomic dissection deep to the SMAS demonstrated a very thin layer
anterior to the parotid gland. At this point the branches of the facial nerve
became closely related to the SMAS and were in danger of being injured by
sharp dissection.
SMAS is a compartment which contains nerves and vessels. From a surgical
point of view the facial nerve is of highest importance because lesions of the
facial nerve have to be carefully avoided .The facial nerve leaves the skull at
the stylomastoid foramen and splits inside the parotid gland into its peripheral
branches. These penetrate the parotid fascia, and at this point they become
related to the SMAS.
e anatomy of the SMAS is of high relevance to rejuvenation surgery like face
lift , rhitidectomy.

22. REFERENCE
SICHER
ELLIS
PETER D QUEIN
Surgical Anatomy of the Superficial Musculo-Aponeurotic System (SMAS)
Husain Ali Khan, MD, DMD*, Shahrokh Bagheri, MD, DMD
Anatomy of the SMAS Revisited
Alireza Ghassemi, Andreas Prescher, Dieter Riediger, and Hubertus Axer
Aachen, Germany
COMPUTATIONAL MODELING OF THE PASSIVE AND ACTIVE COMPONENTS OF THE FACE 18
Cormac Flynn*, Mohammad Ali Nazari†, Pascal Perrier‡, Sidney Fels§, Poul M.F. Nielsen,
Yohan Paya